You can never have enough button design inspirations, this set of design comes from David Conner. There are five designs to choose from, the first one is a ghost style button which on hover transforms the button border to an underscore. The next effect adds a line above and below the button text on hover. The third effect has a 3D touch to it giving the impression of a pushed down button on hover. The fourth button gives a shine effect that slides from the top left to the bottom right on hover. The final button sends out a small pulse like effect from the button border.
If you are having trouble with the pen, try the archived copy on GitHub
See the Pen Collection of Button Hover Effects by David Conner (@davidicus) on CodePen.0